Thermal and Mechanical Characteristics of Polymer Composites Based on Epoxy Resin, Aluminium Nanopowders and Boric Acid

The epoxy polymers are characterized by low thermal stability and high flammability. Nanoparticles are considered to be effective fillers of polymer composites for improving their thermal and functional properties. In this work, the epoxy composites were prepared using epoxy resin ED-20, polyethylene polyamine as a hardener, aluminum nanopowder and boric acid fine powder as flame-retardant filler. The thermal characteristics of the obtained samples were studied using thermogravimetric analysis and differential scanning calorimetry. The mechanical characteristics of epoxy composites were also studied. It was found that an addition of all fillers enhances the thermal stability and mechanical characteristics of the epoxy composites. The best thermal stability showed the epoxy composite filled with boric acid. The highest flexural properties showed the epoxy composite based on the combination of boric acid and aluminum nanopowder

Study of the Effect of Radiation Dose Rate on the Stability of Various Organochlorine Pesticides

Abstract irradiated at dose of 10 kGy with dose rate varied from 8.3 ⋅ 10−3 up to 2.33 Gy/sec. It is found that the shape of the degradation degree relationship on dose rate is similar for different OCPs in polar and non-polar solvents (hexane, 2-propanol) and does not depend on the concentration of initial substance. The maximum of the OCP degradation degree is registered in the dose rate range of 0.23-0.43 Gy/sec. A lognormal distribution is considered as a function best fitting the experimental data. The OCP degradation mechanism could be explained by the ratio of active and recombined particles along the gradient of ionizing radiation intensity. Keywords: organochlorinated pesticide; irradiation, dose and dose rate of gammaradiation; radiation degradation; functional dependenc

Effect of Boric Acid on Volatile Products of Thermooxidative Degradation of Epoxy Polymers

The polymeric materials are characterized by high flammability. The use of flame retardants in order to reduce the flammability of polymers can lead to the formation of toxic gaseous products under fire conditions. In this work we studied the effect of boric acid on the volatile products of thermooxidative degradation of epoxy polymers. The comparative investigations were carried out on the samples of the unfilled epoxy resin and epoxy resin filled with a boric acid at percentage 10 wt. %. The analysis of the volatile decomposition products and thermal stability of the samples under heating in an oxidizing medium was performed using a thermal mass-spectrometric analysis. It is found that the incorporation of boric acid into the polymer matrix increases the thermal stability of epoxy composites and leads to a reduction in the 2-2.7 times of toxic gaseous products

Thermal properties of epoxy composites filled with boric acid

The thermal properties of epoxy composites filled with boric acid fine powder at different percentage were studied. Epoxy composites were prepared using epoxy resin ED-20, boric acid as flame-retardant filler, hexamethylenediamine as a curing agent. The prepared samples and starting materials were examined using methods of thermal analysis, scanning electron microscopy and infrared spectroscopy. It was found that the incorporation of boric acid fine powder enhances the thermal stability of epoxy composites

ТЯЖЕСТЬ ТЕЧЕНИЯ АТОПИЧЕСКОГО ДЕРМАТИТА У ПАЦИЕНТОВ, СТРАДАЮЩИХ ПАТОЛОГИЕЙ ГЕПАТОБИЛИАРНОЙ СИСТЕМЫ

The aim of the research was to define severity of atopic dermatitis (AtD) in the patients with hepatobiliary pathology. 221 patients with AtD were under investigation. 51 of them had associated biliary dyskinesia, 45 patients had chronic viral hepatitis (CVH) without replecative kinesis, 65 patients had chronic viral hepatitis (CVH) with replecative kinesis, and 50 patients had no hepatobiliary pathology. The results obtained showed marked effect of the hepato-biliary system pathology on the severity of the AtD pathology. The patients with biliary dyskinesia have a lichenoid kind of AtD and patients with deep-rooted viral hepatitis have an eczematous kind of AtD.Целью исследования явилось определение тяжести течения атопического дерматита (АД) у пациентов, страдающих патологией гепатобилиарной системы. В исследовании приняли участие 211 пациентов атопическим дерматитом, среди которых 51 больной страдал сопутствующей дискинезией желчевыводящих путей (ДЖВП), у 45 пациентов - хронический вирусный гепатит (ХВГ) без репликативной активности, 65 больных - ХВГ с репликативной активностью. 50 пациентов, составивших группу сравнения, не имели патологии гепатобилиарной системы. По результатам проведенного исследования выявлено значимое влияние на тяжесть течения АД патологии гепатобилиарной системы, особенно ХВГ с репликативной активностью. Определено преобладание лихеноидной формы АД у пациентов с сопутствующей ДЖВП и экзематозной -у пациентов с ХВГ

Effect of electron beam irradiation on thermal and mechanical properties of epoxy polymer

This study investigates the thermal and mechanical properties of epoxy polymer after exposure to different doses of electron beam irradiation. The epoxy polymer was prepared using epoxy-diane resin ED-20 cured by polyethylenepolyamine. The irradiation of the samples was carried out with doses of 30, 100 and 300 kGy. The effects of doses on thermal and mechanical properties of the epoxy polymer were investigated by the methods of thermal gravimetric analysis, tensile test, and dynamic mechanical analysis. The thermal properties of the epoxy polymer slightly increased after irradiation at the heating in air. The tensile strength and Young's modulus of the epoxy polymer increased by the action of electron beam up to dose of 100 kGy and then decreased. The elongation at break decreased with increasing the irradiation dose

Effect of electron beam irradiation on thermal and mechanical properties of epoxy polymer

This study investigates the thermal and mechanical properties of epoxy polymer after exposure to different doses of electron beam irradiation. The epoxy polymer was prepared using epoxy-diane resin ED-20 cured by polyethylenepolyamine. The irradiation of the samples was carried out with doses of 30, 100 and 300 kGy. The effects of doses on thermal and mechanical properties of the epoxy polymer were investigated by the methods of thermal gravimetric analysis, tensile test, and dynamic mechanical analysis. The thermal properties of the epoxy polymer slightly increased after irradiation at the heating in air. The tensile strength and Young's modulus of the epoxy polymer increased by the action of electron beam up to dose of 100 kGy and then decreased. The elongation at break decreased with increasing the irradiation dose

Age dynamics of strain differences in the morphofunctional state of pancreatic beta- and amylin-producing cells in SHR and Wistar rats

Large-scale epidemiological studies have shown that cardiac pathology and progressive atherosclerosis in patients with diabetes mellitus occurred already at the stage of prediabetes. Obesity and insulin resistance affect cardiometabolic health due to pleiotropic effects of insulin. Despite the vast range of research, some aspects remain hidden links in the overall pathogenesis of metabolic and hemodynamic disorders. The aim of the work was to study the morphofunctional state of pancreatic islets (PIs), beta- and amylin-producing cells in male rats of Wistar strain (normotensive) and SHR (with spontaneous development of hypertension) in age dynamics. Materials and methods. The study was carried out using 38 male Wistar rats and SHRs aged 7 and 24 months. Non-invasive blood pressure (BP) detection procedures were done using the BP-2000 Blood Pressure Analysis System. The morphofunctional state of PIs was examined in serial 5-μm thick pancreatic tissue sections. Beta- and amylin-producing cells were detected after histological preprocessing and the use of monoclonal FITC-conjugated antibodies. Image file processing was done via ImageJ software (National Institutes of Health, USA). Levels of glycemia were monitored with a SUPER GLUCOCARD-II glucometer. Results. SHRs were hyperglycemic both at 7 and at 24 months, 8.41 ± 0.15 mmol/l and 8.90 ± 0.14 mmol/l, respectively, with elevated BP, 155 ± 5 / 80 ± 5 mm Hg and 165 ± 5 / 90 ± 5 mm, respectively. Old SHRs developed PI hypertrophy mainly associated with the increased number and percentage of beta-cells, apparently in response to hyperglycemia. Both in the PIs of adult and old SHRs, the number of amylin-producing cells was lower while the content of amylin was higher than those in the age-matched Wistar rats. Conclusions. Male SHRs are characterized by a persistent increase in blood pressure and abnormalities of carbohydrate metabolism already at adult age, one of the manifestations of which is hyperglycemia worsening with age. Chronic hyperglycemia in SHRs due to the higher insulin requirement finds its expression in low content of this hormone in the islets at adult age and decreased its content in beta-cells in old animals

The mechanisms of fiber flax adaptation to high soil acidity (a review)

Excessive soil acidity is one of the main factors causing significant losses in crop production. Using fiber flax, the effect of soil acidity on the yield and fiber quality of various samples representing the world gene pool of this crop is shown. The optimum acidity for fiber flax is within a narrow range – pHKCl 5.3–5.6. On strongly acid soils (pHKCl less than 4.5) with threshold values of the toxic aluminum (Al3+) content, 10–11 mg/100 g, a decrease in the flax yield is over 50%. Currently, along with the mechanisms of detoxification of toxic aluminum in acid soils, genetic aspects of aluminum resistance have also been determined. It is shown that one of the most significant components of the common defense response of plants to various stresses is their antioxidant systems. An important role in the antioxidant defense system belongs to glutathione transferases. Using high-through put sequencing and quantitative PCR, a change in the expression of genes and microRNAs in flax plants was revealed in response to the toxic effect of aluminum ions. Using flax genotypes contrasting in acid resistance, an increase in the expression of genes encoding UDP-glycosyltransferases (UGT) and glutathione-S-transferases (GST) was established under aluminum stress. The increase in expression was more pronounced in aluminum-resistant flax cultivars than in sensitive ones. Also, the differences in the change of miR390 and miR393 expression between resistant and sensitive genotypes were revealed under the toxic effects of aluminum ions. Understanding the resistance mechanisms makes it possible to accelerate the development of flax and other crop cultivars adaptive to edaphic stress, which is important for obtaining high and guaranteed yields of agricultural products

The role of language representation of the time model in the process of meaning creation

The aim of the article is to demonstrate the language picture of the world, which owes its structural integrity to its relational framework. The archetype “time” is central to the Christian mythology, in fairy tales and other linguocultural artefacts. The thought-language essences representing the category TIME in the modern German language, connect different time modes (past, present, future), allowing to distinguish different worlds. The memory of the ways of the development of the human soul is concentrated in the